Carrie Underwood Joins the Rolling Stones Onstage in Toronto

Country superstar Carrie Underwood gave fans of the Rolling Stones a little extra bang for their buck in Toronto Saturday night (May 25), joining the iconic rockers onstage for a performance of 'It's Only Rock 'n' Roll (But I Like It).'

Clad in black boots and a Stones tour t-shirt, Underwood brought out her rock and roll side for the song, matching iconic front man Mick Jagger move for move with an energetic performance that showed a different side to the 'Good Girl' hitmaker -- who couldn't stop smiling the entire time she was singing.

Afterward, Underwood didn't try to hide her elation. "I just sang with the @RollingStones! Holy cow! I walked off stage and said, "What just happened?!" Still can't believe it!" she posted to Twitter.

An hour later she added, "8 years ago today, I won @AmericanIdol and tonight, I sang with the @RollingStones! Wow, so much has happened! #Thankful."

The Stones are currently celebrating their 50th anniversary with a tour called 50 & Counting, which has featured a number of guest appearances from stars as diverse as Katy Perry and Dave Grohl. Country superstar Keith Urban also joined the group in Los Angeles on May 3 for a performance of 'Respectable.'